The object of the present invention are new 7-nitro-2,1,3-benzoxadiazole or 7-nitro-2,1,3-benzthiadiazole derivatives and dyeing agents for keratin fibers, especially human hair, containing these compounds.
For the color-changing treatment of keratin-containing fibers, such as human hair, wool or fur, two dyeing methods are generally employed. In the first method, the dyeing is produced with so-called oxidative or permanent dyeing agents using a mixture of different developer and coupler substances and an oxidizing agent. If necessary, so-called substantive (non-oxidative) dyes may be added to round off the dyeing result or to produce special color effects. The second method makes use exclusively of substantive dyes, which are applied on the fibers in a suitable carrier composition. This method is easily employed, very mild and distinguished by little damage to the keratin fibers. The substantive dyes, used here, must satisfy a plurality of requirements. They must be safe from toxicological and dermatological points of view and make it possible to achieve dyeings of the desired intensity. Among other things, this also presupposes an adequate solubility in water. In addition, the dyeings achieved are expected to have a good light fastness, acid fastness, crocking resistance and good stability when washed.
As a rule, a combination of different, non-oxidative dyeing agents are required for substantive (non-oxidative) dyes for keratin fibers. Since the selection of red and blue dyes, which can be used in dyeing agents for keratin fibers, is limited, there continues to be a need for such dyes.